The present invention relates to vehicular anti-lock braking systems (ABS) in general and more particularly relates to the control section thereof.
Anti-lock braking systems control braking as soon as excessive wheel slippage is detected. An ABS must satisfy the requirement that in the event of panic braking, brake pressures of all wheels which are overbraked will be so adjusted that in all phases of controlled braking, substantially maximum possible physical braking force is used. After excessive wheel slippage has been counteracted, there must be a favorable course of pressure which achieves the highest possible average braking action without commencement of wheel slippage caused by overbraking (hereinafter referred to also as "wheel speed breakdown" or "overbraking") occurring too early.
However, for reasons of safety such overbraking must occur in each case, at the latest, about 300 msec after the start of a pressure build-up phase (also referred to as "reloading phase" or "pressure ramp") in order to assure that vehicle travel is not underbraked because of the anti-lock control. If the normal loading ramp terminates after 300 msec without final wheel overloading, then ordinarily a steep search ramp is traveled over which, in the event of a low-high transition, should find a new locking pressure point as rapidly as possible.
The search ramp therefore differs from the normal loading ramp by having a larger pressure gradient with respect to time. However, particularly in the case of motorcycles, cyclic overbraking leads to a lack of braking comfort and unnecessarily long braking paths.